Valves are well known in the art. They have differing configurations, sealing means and function. To date, there have been no valves specifically designed to equalize pressure on both sides to be utilized in an ammonia system wherein minimization of creation of vapor is essential and desirable.
Numerous innovations for an ammonia excess flow valve have been provided in the prior art that are described as follows. Even though these innovations may be suitable for the specific individual purposes to which they address, they differ from the present invention as hereinafter contrasted.
In my U.S. Pat. No. 3,540,469, Titled "Excess Flow Check Valve," I described an excess flow check valve for liquefied gaseous fluid, such as liquefied petroleum gas and anhydrous ammonia, handling equipment and particularly for safeguarding the withdrawal of such fluid from a storage tank. The valve has a two stage enclosure to permit the use of a weaker actuating spring, which is more sensitive and resilient. A plurality of lateral ports, of relatively large area and minimal quantity, are provided in its housing, to separate the flow into smaller streams of sufficient area to minimize turbulence and provide substantially uniform closing of said valve irrespective of the flow area therearound. Preferably, the ports are of maximum dimensions to permit maximum controlled flow.
The above patented invention differs from the present invention because it does not describe or claim at least one combination of the following features depicted in the present invention, such as a seal ring, a disk having a disk central opening, and a disk pin opening with a hollow roll pin extending therefrom and a retainer.